The in operator can be used to determine whether a given
element is stored in an array. Examples:
(poke) 2 in [1,2,3] 1 (poke) 2 in [4,5,6] 0 (poke) 10#b in [1#B] #! Promotion doesn't happen. !# <stdin>:1:1: error: invalid operand in expression <stdin>:1:1: error: expected offset<int<32>,8>, got offset<int<32>,1>